Besim Dragovic

I am a postoctoral-associate at Virginia Tech. My principle research interests broadly address the tectono-metamorphic processes involved at convergent plate boundaries. This comprises (i) the development and application of methods to better quantify the timescales and rates of metamorphism, (ii) understanding the role of fluids in metamorphic reactions, and (iii) evaluating the assumption of chemical equilibrium during metamorphism. My background is in the application of Sm/Nd garnet geochronology, but my approach also integrates field and petrographic observations, thermodynamic analysis, various other geochemical and analytical techniques, as well as analyzing these datasets in the context of geodynamic models, all to understand these processes at the microscopic to global scale. Below are some broadly themed topics that my colleagues and I have been addressing (expanded on below):


  Dehydration history of metamorphism

  Chemical equilibrium and kinetics of garnet growth

  Low-temperature subduction history

  High-temperature metamorphism during Archean orogenesis

Besim:    CV   email

input

Publications and Related Abstracts

Dragovic, B., Baxter, E. F. Caddick, M.J.(2015) Pulsed dehydration and garnet growth during subduction revealed by zoned garnet geochronology and thermodynamic modeling, Sifnos, Greece. Earth and Planetary Science Letters. v413, 111-122.

Dragovic, B., Caddick, M.J., Baxter, E.F., 2014. Rapid heating at subduction interfaces: A special case or the norm? 2014 American Geophysical Union Fall Meeting, San Francisco. (poster)

Guevara, V., Dragovic, B., Caddick, M.J., Baxter, E.F., 2014. 2.69-2.68 Ga granulite facies metamorphism in the Wyoming Craton revealed by Sm-Nd garnet geochronology and trace element zoning, eastern Beartooth Mountains, Montana and Wyoming, USA. American Geophysical Union Fall Meeting, San Francisco, CA, 2014.

Ashley, K.T., Caddick, M.J., Steele-MacInnis, M., Bodnar, R.J., and Dragovic, B., 2014, A detailed history of deep burial and exhumation recorded by quartz Inclusions in garnet. Geochemistry, Geophysics, Geosystems, 15, 350-360.

Dragovic, B., Samanta, L., Baxter, E.F., Selverstone, J., 2012. Using garnet to constrain the duration and rate of water-releasing metamorphic reactions during subduction: An example from Sifnos, Greece. Chemical Geology 314-317, 9-22.

Dragovic, B., Pennsiton-Dorland, S., Feineman, M., Caddick, M.J., Stowell. H., Tulloch, A., Schwartz, J., Mortimer, N., Barnes, J., Gordon, S., Wada, I., Syracuse, E., Ague, J., Baxter, E., Hacker, B., Bebout, G., 2013. Exterra: Understanding Convergent Margin Processes Through Studies of Exhumed Terranes – GeoPRISMS New Zealand Focus Site. White Paper for NSF GeoPRISMS New Zealand Planning Workshop, Wellington, New Zealand, 2013.

Dragovic, B., Baxter. E.F., Caddick, M.J., 2013. Pulsed garnet growth and dehydration during subduction, Sifnos, Greece. Geological Society of America Annual Meeting, Denver, CO, 2013.

Bloom, R., Hirsch, D., Gatewood, M.G., Dragovic, B., Baxter, E.F., Stowell, H.H., 2013. The kinetics of garnet crystallization, Townshend Dam, VT. Geological Society of America Annual Meeting, Denver, CO, 2013.

Baxter, E.F., Dragovic, B., Caddick, M., 2013. The chronology of dehydration. 23rd Annual VM Goldschmidt Conference, Florence, Italy.

Stowell, H.H., Gatewood, M.G., Dragovic, B., Baxter, E.F., Hirsch, D., Bloom, R., 2013. Garnet compositional zoning and evaluating equilibrium in pelitic schist: an example from Townshend Dam, VT. 47th Annual Meeting of the Geological Society of Amerca South-Central Section, Austin, Texas.

Stowell, H.H., Gatewood, M.G., Dragovic, B., Baxter, E.F., Hirsch, D., Bloom, R., 2012. Evaluating the scale and nature of equilibrium in metamorphic rocks using garnet compositions. 2012 Geological Society of America Annual Meeting, Charlotte, NC.

Baxter, E.F., Dragovic, B., Caddick, M.J., 2012. Linking zoned garnet Sm-Nd geochronology and thermodynamic analysis to constrain subduction zone dehydration flux. 34th International Geological Congress, Brisbane, Australia.

Dragovic, B., Gatewood, M.G., Baxter, E.F., Stowell, H.H., Hirsch, D.M., Bloom, R., 2012. Constraining dehydration rates during regional metamorphism, Townshend Dam, Vermont, U.S.A. 22nd Annual VM Goldschmidt Conference, Montreal, Canada.

Bloom, R., Hirsch, D.M., Dragovic, B., Gatewood, M.G., Baxter, E.F., Stowell, H.H., 2012. Determining garnet crystallization kinetics from growth zoning and Mn-calibrated Sm-Nd ages at Townshend Dam, VT. 22nd Annual VM Goldschmidt Conference, Montreal, Canada.

Dehydration history of metamorphism

Fluids released during subduction zone metamorphic reactions directly influence processes such as arc volcanism, intermediate-depth seismicity, and the return of volatiles to the deep Earth. As the growth of metamorphic minerals, specifically garnet, results from the breakdown of parent hydrous phases, coupling high precision garnet geochronology with phase equilibria modeling allows us to constrain the timescales, rates, and periodicity of metamorphism along with the flux of associated dehydration. This approach has providing a detailed history of subducting lithologies, showing that garnet growth (and associated dehydration) occurred in < 1 Myr during relatively isobaric heating. My work attempts to build on currently existing geodynamic models and experimental investigations on fluid release during metamorphism, applying a field-based study on exhumed metamorphic terranes.

Chemical equilibrium and kinetics of garnet growth

While the use of equilibrium thermodynamics has allowed for estimations of pressure and temperature conditions of metamorphism, it is disequilibrium that drives metamorphic reactions and produces mineral zoning. I am interested in attempting to understand the spatial, temporal, and compositional scales over which rocks achieve chemical equilibrium. One project has involved collaboration between Boston University (Ethan Baxter), University of Alabama (Harold Stowell and Matt Gatewood) and Western Washington University (Dave Hirsch and Rose Bloom), utilizing major and trace element, and isotopic zoning in garnet from a pelitic schist from Townshend Dam, VT, to better quantify this scale of chemical equilibrium. Another project, which I work on in collaboration with Mark Caddick and VT graduate student Kristen McCall attempts to understand the causes and conditions for thermal overstepping of porphyroblast growth (or why these crystals do not often grow at pressures and temperatures simply governed by equilibrium thermodyanamics.)

Low-temperature garnet growth and subduction

Garnet growth metamorphism evens occurs at the lower temperatures during early stages of subduction. As part of a new collaboration with Nick Mortimer (GNS Science, NZ), we are studying metamorphic conditions in the Cretaceous paleo-forearc and accretionary wedge of New Zealand, at which garnet growth occurs at low temperatures (~300-350 ºC), presumably involving little to no overstepping of metamorphism (and a potentially high fluid flux). Utilizing garnet geochronology and phase equilibria modeling, we are developing a pressure-temperature history for early burial during subduction, which will provide insight into currently existing subduction models.

High-temperature metamorphism during Archean orogenesis

The Archean represents a significant period in Earth history, during which large volumes of Earth’s cratonic crust are thought to have formed. However, the mechanisms, thermal gradients, and durations of these orogens are not well understood. In collaboration with Mark Caddick and VT graduate student Victor Guevara, we are attempting to reconstruct the metamorphic evolution of two high temperature/ultrahigh temperature (HT/UHT) Archean terranes, using both traditional and non-traditional geochronologic, geochemical, and petrological techniques.